Assessment of vitamin D deficiency level by the physiological response of parathyroid hormone in Turkish adults

Abstract

Abstract Objective We aimed to contribute to the literature by determining deflection point of parathyroid hormone (PTH) level compared to 25-hydroxy vitamin D3 (25(OH)D3) level for determining the cut-off value of vitamin D deficiency level in Turkish adults. Methods The levels of 25(OH)D3 and intact parathyroid hormone (iPTH) which were requested simultaneously in 1 year of 1684 adults were evaluated retrospectively. 25(OH)D3 levels were first classified as 80–50, 50–30, 30–25, 25–20, 20–15, 15–10, 10–5, 5–0 ng/mL and iPTH levels among those groups were compared. Results First significant difference in iPTH levels was determined between 25(OH)D3 groups of 80–50 and 50–30 ng/mL (p=0.007). Second and third significant differences were determined between 25(OH)D3 groups of 15–10 and 10–5 ng/mL and between 10–5 and 5–0 ng/mL, respectively (p=0.006 and p=0.035, respectively). There were no differences in iPTH levels among seasons (p=0.11). Conclusion In the light of these findings; we can state that iPTH levels are suppressed when 25(OH)D3 over 50 ng/mL, remains stable when 25(OH)D3 levels in between 50–10 ng/mL and gives the first increase response when 25(OH)D3 falls below 10 ng/mL. We believe that cut-off value for vitamin D deficiency in Turkish adults at all seasons depending on PTH response should be used as 10 ng/mL.